**Theorem** ([D-2000])

Let *p* > 7 be a prime satisfying the following two conditions:

1.Thenp= 2 (mod 5) orp= 4 (mod 5)

2. 2p-1 is also prime.

**Theorem** ([J-1973, p. 11])

Let *n* be odd and let *p* be an odd, primitive prime
divisor of *F _{n}*. Then

1.p= 1 (mod 4).

2. ifp= 1 or -1 (mod 10) thenp= 1 (mod 4n).

3. ifp= 3 or -3 (mod 10) thenp= 2n-1 (mod 4n).

**Theorem** ([J-1973, p. 11])

Let *n* be positive and let *p* be an odd, primitive prime
divisor of *L _{n}*. Then

1. ifp= 1 or -1 (mod 10) thenp= 1 (mod 2n).

2. ifp= 3 or -3 (mod 10) thenp= -1 (mod 2n).

If anyone knows of other theorems, please let me know.

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